totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

8 minutes ago, kerbiloid said:

SpaceX is still launching sats with man-rated rockets.
A sat-rated rocket would be cheaper.

[Citation needed]

8 minutes ago, kerbiloid said:

That was Khrushchev's phrase "Now we are making rockets (ICBM) like sausages!"

Yes, I know, lol.

[kerbiloid]

1 minute ago, sevenperforce said:

[Citation needed]

?
It's just a constatation. The Falcon was designed to carry a Dragon. Still no crew dragon.

[RCgothic]

 

 

Edited April 23, 2020 by RCgothic

[sevenperforce]

13 minutes ago, kerbiloid said:

?
It's just a constatation. The Falcon was designed to carry a Dragon. Still no crew dragon.

Citation needed that it would be cheaper to maintain a different, non-man-rated rocket for unmanned launches.

[kerbiloid]

4 minutes ago, sevenperforce said:

Citation needed that it would be cheaper to maintain a different, non-man-rated rocket for unmanned launches.

If they are same cheap why say "man-rated"?

[sevenperforce]

7 minutes ago, kerbiloid said:

If they are same cheap why say "man-rated"?

I have a well-maintained, high-safety-rated SUV with top-of-the-line, nuclear-holocaust-proof carseats that I use to haul my kids around (when the world is open). If I remove the carseats and fold the back rows down, I can fit a full-size dining room table plus chairs in the back end.

It wouldn't be "cheaper" for me to buy and maintain a separate pickup truck for hauling cargo merely because the SUV has a higher child safety rating than the pickup truck.

Similarly, if SpaceX's man-rated launcher can send cargo to space, why would they develop a second, non-man-rated one to do the exact same job?

[kerbiloid]

10 minutes ago, sevenperforce said:

I have a well-maintained, high-safety-rated SUV with top-of-the-line, nuclear-holocaust-proof carseats that I use to haul my kids around (when the world is open). If I remove the carseats and fold the back rows down, I can fit a full-size dining room table plus chairs in the back end.

It wouldn't be "cheaper" for me to buy and maintain a separate pickup truck for hauling cargo merely because the SUV has a higher child safety rating than the pickup truck.

Both of them are man-rated, they are cars. Noone of them is allowed to loose a cargo once per ten or twenty trips.

But you can have failed, say, 1 cargo rocket of 20 but, say, 1 crew rocket of 100.
So, the part assemblies for a crew rocket typically have to be more reliable, have excessive parts, have to be selected from greater amount of manufactured detailes in more narrow range of parameter values, etc.

You don't need fire tests and restartable engines for a sausage rocket.

Say, iirc V-2 was lost in 40 cases of 100. It was appropriate for the expendable rocket with unsignificant payload, but it wouldn't be to launch crews in time of peace.

Edited April 23, 2020 by kerbiloid

[sevenperforce]

1 minute ago, kerbiloid said:

Both of them are man-rated, they are cars.

A pickup truck bed is not rated for strapping down infant carseats.

[kerbiloid]

1 minute ago, sevenperforce said:

A pickup truck bed is not rated for strapping down infant carseats.

Infants don't apply to the court.
Adults would do this in any case.

So, of course I don't know exactly, but looks that in this case the "baby-rating" is defined not really by the car properties, but by lawyer games.

[Wjolcz]

@sevenperforce just don't bother. We've been through this a couple of times already.

[mikegarrison]

First, I know it's the common terminology, but maybe it might be better to say "crew rated"?

Secondly, besides jumping through documentation gates, what's the difference between developing a really reliable rocket for uncrewed payloads and one that is crew-rated? And doesn't reliability figure in to payload insurance costs?

Atlas has been rated for crew for decades and they still use it to launch uncrewed payloads. This is hardly unique to SpaceX.

[sevenperforce]

18 minutes ago, kerbiloid said:

Infants don't apply to the court.
Adults would do this in any case.

So, of course I don't know exactly, but looks that in this case the "baby-rating" is defined not really by the car properties, but by lawyer games.

Last I checked, truck beds are not rated for adult passengers either, though that doesn't stop rednecks.

The fact remains: if you have reusable vehicles, it makes no economic sense to develop, build, and maintain an entirely separate model for launching lower-value payload if your higher-rated payload will do the same job. 

If you have expendable vehicles then it depends on how modular your components are.

16 minutes ago, Wjolcz said:

@sevenperforce just don't bother. We've been through this a couple of times already.

I never learn my lesson.

Just now, mikegarrison said:

Secondly, besides jumping through documentation gates, what's the difference between developing a really reliable rocket for uncrewed payloads and one that is crew-rated? And doesn't reliability figure in to payload insurance costs?

Exactly.

[RealKerbal3x]

1 hour ago, RCgothic said:

 

 

I never want to hold pop again...

[kerbiloid]

13 minutes ago, sevenperforce said:

The fact remains: if you have reusable vehicles, it makes no economic sense to develop, build, and maintain an entirely separate model for launching lower-value payload if your higher-rated payload will do the same job.

Exactly.
But if you use this rocket only for crew-less tasks, there is no need to design it crew-rated.

So, it's like if they use SUV for potatoes.

13 minutes ago, mikegarrison said:

First, I know it's the common terminology, but maybe it might be better to say "crew rated"?

I always say so _{just for fun}, but I thought "man-rated" is an official term.

Edited April 23, 2020 by kerbiloid

[mikegarrison]

3 minutes ago, kerbiloid said:

I thought "man-rated" is an official term.

It probably is, but that doesn't mean we shouldn't change it.

[tater]

44 minutes ago, sevenperforce said:

A pickup truck bed is not rated for strapping down infant carseats.

Here in NM, my wife said many of charts at University Hospital (this was when she was a resident, and charts were actual paper) had a note in the margin on motor vehicle accidents (MVAs) that said "FOOP."

Fell Out Of Pickup.

A common cause of trauma in rural NM from riding in the bed.

Edited April 23, 2020 by tater

[sevenperforce]

7 minutes ago, kerbiloid said:

But if you use this rocket only for crew-less tasks, there is no need to design it crew-rated.

So, it's like if they use SUV for potatoes.

 

I am currently only using my SUV for potatoes and other groceries due to the shutdown. But the SUV was designed from the beginning to be safe enough to use for my kids. Should I throw away the SUV and buy a pickup for grocery runs until the pandemic is over?

[kerbiloid]

2 minutes ago, sevenperforce said:

 

I am currently only using my SUV for potatoes and other groceries due to the shutdown. But the SUV was designed from the beginning to be safe enough to use for my kids. Should I throw away the SUV and buy a pickup for grocery runs until the pandemic is over?

No, because you have bought it first of all for kids.

But if you were a farmer, probably some not very expensive pickup would be enough good if use it for potatoes only.

[RealKerbal3x]

@kerbiloid Falcon 9 wasn't designed from the beginning to be human-rated. Later, when they received the contract from NASA to fly crew, modifications had to be made, but they weren't so big that an entirely new vehicle had to be developed. That would have been an order of magnitude more expensive. Plus, SpaceX was being funded by NASA, so they didn't really have to pay as much to human rate F9. Sure, human-rated launch vehicles have to undergo more stringent tests, but only when they actually fly crew. 

Basically what I'm saying is that human-rated launch vehicles aren't arbitrarily more expensive to launch just because they have that certification. The cost is in developing the vehicle to be human-rated, and not flying it - unless it is actually flying crew on a certain mission.

Edited April 23, 2020 by RealKerbal3x

[RCgothic]

When you're throwing away a rocket each time it doesn't matter (too much) if it's a little unreliable if it's not cost effective to improve it.

When you're reusing a rocket you want a much higher level of reliability because any time it fails you lose your free lunch.

Falcon9 is reliable because it is cost effective with reuse. That this is also good for crew-rating is happy happenstance.

[tater]

Crew rating just means having a certain safety level. That can be designed in by testing all the parts, and making assumptions about failure rates, etc, or you can simply fly the thing many, many times, and have an actual record of safe launches, then do the math from there.

Also:

 

[CatastrophicFailure]

52 minutes ago, tater said:

had a note in the margin on motor vehicle accidents (MVAs) that said "FOOP."

Fell Out Of Pickup.

Better than FOOF... 

@Kerbaloid also, *cough*SOYUZ*coughcough*

Which, interestingly enough, goes to the launch pad on rails, which this thread has once again gone entirely off of. 

*typed from an SUV used mainly for simple commuting.

...if I ever get that Model X I’m getting a sticker that says “I identify as a rusty ol’ farm truck.”

 

[Rakaydos]

47 minutes ago, CatastrophicFailure said:

...if I ever get that Model X I’m getting a sticker that says “I identify as a rusty ol’ farm truck.”

 

Would be better on a cybertruck.

[kerbiloid]

Spoiler

 

1 hour ago, CatastrophicFailure said:

@Kerbaloid also, *cough*SOYUZ*coughcough*

 

Every time when somebody refers to @Kerbaloid instead of me, one Kerbal suffocates on Duna.

Seriously, gentlehumans, stop poking him, I even feel guilty.

***

SOYUZ is not my fetish, lol. I'm a fan of another firm, lol.

Also, Soyuz is originally ICBM. Obviously not human-rated.
As well as Atlas, Titan, and Redstone.

 

Edited April 23, 2020 by kerbiloid

[Dirkidirk]

7 minutes ago, kerbiloid said:

  Hide contents

  

  

Every time when somebody refers to @Kerbaloid instead of me, one Kerbal suffocates on Duna.

Seriously, gentlehumans, stop poking him, I even feel guilty.

***

SOYUZ is not my fetish, lol. I'm a fan of another firm, lol.

Also, Soyuz is originally ICBM. Obviously not human-rated.

 

technically @Kerbaloid has never visited the forums and has joined in 2012, so it probably doesn't matter, @Kerbaloid...

Edited April 23, 2020 by Dirkidirk